The Big Picture

It takes a keen eye to notice, but it’s there, impacting systems and increasing inefficiencies. Because it’s hard to see, it likely won’t top every plant’s priority list, but controlling biofilm can have system-wide impacts.

Bob Jewell, energy systems chief at Chippewa Valley Ethanol Co. in Benson, Minnesota, says recognizing and controlling biofilm can pay off, not just by preventing fouling. “Being proactive can also result in numerous indirect benefits such as optimized usage and improved effectiveness of other treatment additives, reduced system corrosion rates, increased equipment longevity, heat exchangers staying cleaner and for longer periods, and reduced maintenance requirements,” he says.

Jewell says, historically, not all plants have paid much attention to biofilm control. He says that while there are plants with an effective biofilm control program, many plants’ cooling systems might not be operating as efficiently as they could be, because of biofilm. “I also think it is relatively common that the implications of biofilm are not fully appreciated or are undervalued.” But that’s changing, he says. With new technologies and more industry focus on the biofilm issue, more plants are starting to take a proactive look at detecting and controlling biofilm. “I don’t think that the industry’s response to the issue is related so much to attitudes, but rather to the problem just being brought to the forefront relatively recently and to education, awareness and perceptions catching up, which are all key in being able to identify, address and control it,” he says.

Jim Lukanich, director of applied technology at U.S. Water Services, agrees. “That knowledge has been around for quite some time, but there’s just an increased focus on research because of what we understand in cooling water, and in other process water systems: that if we can control biofilm, it reduces the amount of problems we have with corrosion as well as mineral deposits,” he says.

“However, due to the amount of research and observations in the field over the years, there is an increased understanding of bacteria, fungi and algae in general, … we understand biofilm can contribute to these other problems to a much larger degree than previously thought.” He adds that the recent focus on biofilm control isn’t unique to the ethanol industry. All industries that use cooling water in their operations have been more attentive to biofilm recently.

It stems from an increased awareness about preventing Legionella, the bacteria that causes Legionnaires’ disease, Lukanich says. “By controlling biofilm and having an emphasis on biofilm, we not only minimize the potential for fouling, scale and corrosion, but also reduce the risks associated with the amplification of Legionella and associated disease.”

According to Jewell, the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) in 2015 developed a standard for preventing Legionella. While it isn’t enforceable unless it’s made a law by local or state governments, Jewell believes wider adoption is likely to happen in the future. “According to ASHRAE’s website, ASHRAE is asking its chapters to encourage municipal, state and federal governments and legislative bodies to adopt [the standard] into law,” he says. “The parts are all there and it was written with pathways for adoption in mind. Future cases or outbreaks are only likely to build more momentum toward its adoption.”

Kevin Milici, vice president of marketing and technology for U.S. Water Systems, agrees. “In certain parts of the world … pathogen or risk management isn’t a recommended best practice, it’s the law. … And there’s been a lot of discussion about, ‘Is that basic regulation coming to the United States?’ And I think the consensus is that, with time it will.” He adds that there are areas of the U.S.—like New York City—that have adopted the standard as law. But those laws apply to building water systems in places like hotels, healthcare facilities and apartment buildings, rather than industrial manufacturing facilities, like ethanol plants.

Jewell says it’s natural for plants to begin focusing on controlling biofilm in their quest to optimize their operations. Many plants, he says, have undertaken improvements to debottleneck and increase efficiencies in other areas. With those visible issues resolved, plants are turning to less obvious ways to make their plants run more smoothly, and for many, that means evaluating their cooling systems and biofilm-control mechanisms. “As they’ve optimized and debottlenecked their processes and used up all that low-hanging fruit, it just leads them to looking other places that they hadn’t really entertained in the past,” Jewell says.

A Proactive ApproachFor Jewell and CVEC, the interest in biofilm control began when the plant was evaluating debottlenecking opportunities. During that process, they discovered the plant’s cooling system was underperforming. “In trying to keep the plant efficient, and expand and debottleneck things, and optimize the plant, … we kept going after that cooling water system to try to optimize that as well, because that was one of the things that was holding us back. But in that whole exercise, it kind of revealed that we had some biofouling and biofilm issues, so we’ve been attuned to that for quite a few years.”

A new cooling tower was eventually installed to replace the aging towers that had been in place since the plant’s construction in 1996, and Jewell says the plant’s current biofilm control measures grew, in part, out of a desire to protect the new components. “We wanted to make sure we protected those assets and didn’t end up reverting back to our old practices, which were not effective in preventing that biofilm,” he says.

While Jewell says he doesn’t necessarily consider CVEC a model plant for fighting biofilm, he says they are proactive in their efforts. “I think that we are definitely one of the plants on the forefront regarding the utilization of some of the currently best available technology for measuring, monitoring, and control of biofilm. I do feel we are helping to bring awareness to the potential issues and implications of biofilm and to shape how that type of technology is utilized within the industry.”

Part of the plant’s success comes from a continuous, real-time monitoring and control system for biofilm, which was installed by Solenis. Jewell says early detection is crucial in deploying biofilm countermeasures. “Recognizing biofilm formation at the onset is key, and a huge benefit in gaining control of it early before fouling occurs or other damage can be done,” he says.

‘A Holistic View’That’s especially true since the conditions affecting biofilm growth are constantly changing. “Bacteria are moving targets, and they adapt quickly to change,” Lukanich says. As bacteria reproduce, they can become resistant to control methods that had worked in the past. “All of a sudden, they’ve turned on a mechanism by which they become more resistant to the level of chlorine being used, and so now … you begin to get fouling, when for a year, everything was fine. … Nothing relating to an increase in organic carbon or anything else, it’s just an organism turned on a mechanism of adaptation. We have to pay attention to that activity.”

But an increase in organic carbon—from a heat exchanger leak, for example—can be detrimental to biofilm control. “There’s nothing that causes the microbial activity in that tower to spike in an ethanol plant more than a heat exchanger leak,” Lukanich says. “You can go from being well-controlled to being out of control with respect to a fouling pretty much overnight.” He adds that small leaks can go unnoticed, so constant monitoring of the system is crucial to control biofilm. “If you go from 40 ppm of organic carbon in a tower to 100, there may not be anything in your daily testing that will tell you that, but it would change the activity of those organisms and therefore how you treat them on an ongoing basis,” he says.

That constant monitoring can be difficult with some of the older methods, Jewell says. Prior to the plant’s current system, CVEC used coupons and other means to monitor biofilm and corrosion. The problem, he says, is the length of time it takes to get results. “You need to expose them to that for anywhere from seven to 90 days, depending on what you are trying to measure, so you end up responding to something that happened as much as three months previously. It’s hard to react to those types of delayed results.”

Perhaps more important than continuous monitoring is understanding the cooling system and how it’s operating. “I think it’s one of the single most important things you can do, is just do an evaluation of all the equipment within the system to determine if you have deficiencies in cooling capacity or just performance of the equipment, and compare it to design or the as-built specifications,” Jewell says. “Because that’s the only way that you’re going to understand, number one, where your deficiencies lie, and that’s going to be how you determine if it’s just a deficiency in design or if it’s a deficiency due to some other reason such as biofilm.”

Lukanich agrees. “You have to look at the facility from a holistic view. What are the things contributing to microbial growth and biofilm accumulation in your systems, what’s the history, what are you doing with respect to that? … I think it’s a starting point.”